According to the WHO the rate of dengue fever increased in the second half of the twentieth century, almost thirty times. This huge leap is caused by urbanization, population growth, the increasing popularity and number of travellers and global warming. Dengue is currently the second most commonly diagnosed infection after malaria in this group of diseases.
Research to overcome the disease and find an effective vaccine for dengue has been sought for for a long time. In December 2015, Sanofi Pasteur as the first company announced success in the field. Yet, it is worth mentioning that there are five other potential vaccines during trials, of which two are currently undergoing Phase III of clinical tests.
Dengvaxia (Sanofi Pasteur) is designed to stimulate the immune system by producing antibodies to all four serotypes of dengue virus. But then again it is not 100% effective – in clinical tests, the vaccine reduced the risk of infection by about 60%. The positive news is that the observed efficacy of the vaccine was higher for the two more dangerous dengue serotypes. Doubts regard effectiveness of the vaccine for children, particularly under 9 years of age, and the elderly people. Therefore, the vaccine has been registered and approved in the Philippines, Brasil, and Salvador and in Mexico only for patients between 9 and 45 years old.
In early April, a program of vaccination of approximately one million public school students from areas where dengue is endemic has been launched in the Philippines. The vaccine is administered in three doses according to 0/6/12 months scheme.
Undoubtedly, this is a big step forward and if further studies prove the effectiveness of the vaccine it is likely that it will become available for travellers going to Southeast Asia, South America or Africa.
Description of the disease
Dengue is an infectious disease – caused by a virus (Flaviviridae, type: Flavivirus). The most dangerous are serotypes 3 and 4 of the virus (there are a total of four) causing hemorrhagic fever. Important information: The infection of one serotype, though it gives a person lifetime immunity on this particular serotype of the virus, at the same time increases the risk of complications in case of infection of other serotypes of the virus.
Dengue is transmitted by the bite of infected mosquitoes of the genus Aedes, usually Aedes aegypti. They typically live on the area between 35 ° N and 35 ° S and under 1000 m.n.p.m. Mosquitos are able to bite and therefore spread the virus at any time of day and year, though usually they bite in the morning and evening. The virus cannot be transmitted from human to human.
The disease is a bit harder for adults, but children are at greater risk of serious complications. The incubation period is between a few up till 14 days – that means that travelers, who observed uncomplicated fever after more than 2 weeks since returning home from endemic areas have a low probability of dengue.
Symptoms: fever, bone – joint pain, headache, swollen lymph nodes and liver. Typical dengue fever is two-phased: high temperature and joint pain, especially the knee joints. Than fever decreases after 2-4 days. After a short (up to 20-30 hours) remission, the fever returns, and this time accompanied by a maculopapular rash on the hands and feet passing on the limbs, trunk, rarely face. The most severe clinical form of dengue is hemorrhagic fever. This is a severe form and is characterized by high mortality rate. The initial symptoms are stronger and include vomiting, after 2-3 days comes abdominal pain, enlarged liver and hemorrhagic diathesis – petechiae caused by the cracking of blood vessels. It can lead to coma. Bleeding into body cavities appear after 4-5 day of the disease – in the absence of treatment shock and following even death may occur. However, it should be noted that most patients recover after Dengue (all serotypes) without serious consequences – yet it is necessary to implement the treatment. You really cannot take this disease too lightly.